Curcumin, in addition to its use as a colorant, is also useful as a flavor, depending upon the variety of the plant and the method of preparation. In U.S. Pat. No. 3,906,116 to Quesnel et al, it is disclosed that flavor oleoresins, such as oleoresin turmeric, can be microencapsulated at high flavor levels by spray drying an emulsion where the oleoresin forms the dispersed phase and an aqueous emulsion stabilizer solution comprises the continuous phase. While the patent mentions stability, the product is primarily meant for flavoring, and pHstable colors are not provided.
In U.S. Pat. No. 2,385,412, Hall relates his solution to a problem encountered in the manufacture of dry seasoning compositions containing the oleoresin capsicum. He found that acid conditions, caused by a carrier such as sodium chloride or corn syrup, would result in a gradual bleaching of the color. To correct this, he suggested wetting the carriers with an alkaline buffer solution of the capsicum. Tests in the application show a reduced pH change, but this requires coating all of the carrier with the buffer solution.
In U.S. Pat. No. 4,163,803, Goldscher discusses the use of turmeric to both flavor and color acid foods, but does not identify a method for making a pH-stable colorant. The disclosed improvement relates to the elimination of a bitter note in turmeric by the addition of glycine.
In U.S. Pat. No. 4,138,212, Stransky discloses that washing ground turmeric root in a soap solution extracts curcumin in water-soluble form and in increased yields. It is indicated that this alkaline form is more color-stable than conventional polysorbate water-soluble prepared by the prior art alcohol extraction procedure. An oil soluble form is prepared by precipitating the curcumin by adding an acid, while yet maintaining an alkaline pH. There is no disclosure herein of a dry product suitable for use in dry mixes and which is stable in contact with acid as well as alkaline mixes.
There remains a need for a storage stable, dry curcumin colorant which can be employed in small amounts in dry food mixes, regardless of the pH of the mix, to provide food products with a pleasing yellow coloration.